Semiconductor and other devices now may include photonic devices to generate, guide, split, combine, focus, or detect electromagnetic radiation; detection of electromagnetic radiation may involve conversion of electromagnetic radiation into an electrical charge or current.
Some silicon and semiconductor devices may include more than one such photonic device. Photonic devices may be of different physical sizes, often determined by optical or other functional properties. In some silicon and semiconductor devices, a waveguide may optically couple a first photonic device of a first size to a second photonic device of a second size. A waveguide with a continuous size between the photonic devices may be chosen, notwithstanding that the waveguide optically couples photonic devices of different sizes. The continuous size may be a compromise relative to one or both of the photonic devices. This compromise may result in losses, such as insertion, transition, and back reflection losses. A waveguide with a 3-dimensional (“3D”) taper between the photonic devices may act as a more efficient waveguide, relative to a waveguide with a continuous size. However, fabrication of a waveguide with a 3D taper has involved demanding fabrication processes, such as gray scale lithography and selective epitaxial growth.
Semiconductor and silicon devices often are subject to imperatives to reduce size, fabrication steps, fabrication cost, and to improve fabrication reliability (also referred to as a “yield rate” for a fabrication process). Optimizing this set of demands is complex and costly.